1. Field of the Invention
The present application relates, in general, to audiometry. The present application relates, in particular, to speech audiometry.
2. Description of the Related Art
Audiometry is the testing of hearing acuity by use of an audiometer. An audiometer is an instrument for gauging and recording the acuity of human hearing.
There are various types of testing used in audiometry (e.g., pure-tone testing, or speech-based testing). In pure-tone testing, a person is usually fitted with headphones or positioned between speakers, and thereafter a series of single-tone (or frequency) sounds are played through the headphones or speakers. The person's responses to the played-back sounds are recorded (typically by a human tester, but sometimes by machine), and an assessment of the person's hearing acuity is made on the bases of the person's responses. In speech-based testing, like in pure-tone testing, a person is usually fitted with headphones or positioned between speakers. However, unlike pure-tone testing, in speech-based testing a series of spoken words are played back through the headphones or speakers. The person's responses to the played-back words are recorded (typically by a human tester), and an assessment of the person's hearing acuity is made on the bases of the person's responses.
One type of speech-based testing is speech intelligibility (SI) testing. SI testing generally provides a measure consisting of the percentage or proporation of words that are correctly reported from a series of spoken words. In typical SI testing, a person whose hearing is being tested is usually fitted with headphones or positioned between speakers, and thereafter the person is presented a series of words played through the headphones or speakers. The played back words are all intended to be at the same sound intensity, or loudness, which is generally ensured by making sure that the loudness control of the system through which the words are being played is the same for all played back words; that is, the loudness at which the system through which the words are being played back is controlled (e.g., the gain of amplifier driving the speakers or headphones through which the words are being played back). In response to each presented word, the person's whose hearing is under test indicates which word the person believes corresponds to the word which he or she has just heard through the speakers or microphones by repeating the word or selecting the word from a list supplied by the person conducting the test. In between the playback of each word, the individual conducting the SI testing records whether the test subject either correctly or incorrectly identified each such played back word. At the end of the test, the individual conducting the SI testing records the percentage correct, and such percentage thereafter serves as a measure of speech intelligibility.